Composition, compound and use

ABSTRACT

PCT No. PCT/GB95/02852 Sec. 371 Date Jun. 27, 1997 Sec. 102(e) Date Jun. 27, 1997 PCT Filed Dec. 7, 1995 PCT Pub. No. WO96/20436 PCT Pub. Date Jul. 4, 1996A toner resin composition comprising a toner resin and the metal salt or complex of a carbocyclic hydroxy caboxylic acid containing at least one methylene group optionally substituted by hydroxy or amino such as 4-(N-methyl-N-2-hydroxyethyl)aminomethyl-3-hydroxy-2-naphthoic acid. Iron and zinc salts are preferred.

This application is the national phase of international applicationPCT/GB95/02852, filed Dec. 7, 1995 which was designated the U.S.

The present invention relates to a composition comprising a toner resinand an aromatic carbocyclic hydroxy carboxylic acid (hereinafter "AHCA")containing at least one methylene group optionally substituted byhydroxy or optionally substituted amino (hereinafter "AHCAM") includingsalts and metal complexes thereof and the use of such compounds asnegative charge control agents. Some of the compounds are novel.

EP 490370 discloses metal salts and complexes of pamoic acid and theiruse as negative charge control agents.

EP 490508 discloses compounds having a fused aromatic ring system havinghydroxy, carboxy and hydroxyalkyl substituents such as3hydroxy-4-hydroxymethyl-2-naphthoic acid including salts and metalcomplexes thereof and their use as corrosion inhibitors. It has now beenfound that such compounds and derivatives thereof are useful as negativecharge control agents (hereinafter "CCA") in electroreprographic imagingprocesses.

Thus, according to the invention there is provided a toner resincomposition comprising a toner resin and an AHCAM including salts andmetal complexes thereof with the exception of pamoic acid.

The carboxylic acid group is preferably attached to a carbon atomadjacent to that carrying the hydroxy group in the AHCA.

The AHCA may be a single aromatic ring which is preferably a phenyl ringas in salicylic acid and derivatives thereof or the AHCA may have one ormore rings fused to a carbocydic aromatic ring which may contain 5 or 6atoms and may be saturated or unsaturated and may be carbocyclic orheterocyclic. Preferred examples of such compounds contain two rings,particularly those where the fused ring contains 6 atoms as innaphthalene, tetrahydronaphthalene, quinoline and tetrahydroquinoline.Specific examples of such AHCA's include 2-hydroxy-1-naphthoic,1-hydroxy-2-naphthoic and 8-hydroxy-1-naphthoic acids and especially3-hydroxy-2-naphthoic acid.

The AHCAM is obtainable by reacting the AHCA with formaldehydeoptionally in the presence of a primary or secondary amine. Under suchconditions the methylene group is located in the ortho- and/orpara-position to the hydroxy group in the AHCA.

Preferably the AHCAM contains the one methylene group and it is alsopreferred that such methylene group is in the ortho position relative tothe hydroxy group of the AHCAM

According to one aspect of the invention there is provided a compositioncomprising a toner resin and a AHCAM of formula 1 ##STR1## or a salt ormetal complex thereof wherein

X is hydroxyl, --NR¹ R² or a group of formula 2 ##STR2## R is halogen,hydroxy, nitro, carboxy, nitrdle, optionally substituted C₁₋₁₈-hydrocarbyl or two adjacent groups R together with the carbon atoms towhich they are attached form an optionally substituted 5- or 6-memberedfused ring;

n is 0to 3;

R¹ and R² is each, independently, hydrogen or optionally substitutedC₁₋₁₈ -hydrocarbyl or R¹ and R² together with the nitrogen atom to whichthey are attached form a ring; and

R³ is hydrogen, aralkyl or optionally substituted C₁₋₁₈ -alkyl with theexception of pamoic acid.

Preferably, R¹ and R² are not both hydrogen.

When R, is hydrocarbyl it can be alkyl, alkenyl, alkynyl, aralkyl oraryl.

When R¹ and R² is hydrocarbyl it can be alkyl, cycloalkyl, aralkyl oraryl.

When R, R¹, R² or R³ is alkyl, it may be linear, branched or alicyclicand is preferably C₁₋₁₂ -alkyl, more preferably C₁₋₈ -alkyl andespecially C₁₋₆ -alkyl. Examples of such groups include methyl, ethyl,propyl, n-butyl, i-butyl, n-hexyl, i-hexyl, 2-ethylbutyl, 2-ethylhexyl,nonyl, dodecyl, octadecyl and cyclohexyl.

When R is alkenyl it is preferably C₃₋₆ -alkenyl.

When R, R¹, R² or R³ is aralkyl it is preferably benzyl or2-phenylethyl.

When R, R¹ or R² is aryl it is preferably phenyl.

When R, R¹ or R² is substituted hydrocarbyl, or when R³ is substitutedalkyl, the substituent or substituents is preferably at least one ofhydroxy, carboxy, halogen or nitrile or the hydrocarbyl groups maycontain a divalent atom or group such as ##STR3## The preferredsubstituent in R,R¹, or R² is hydroxy.

When R is substituted hydrocarbyl it can also be another group --CH₂ X,especially --CH₂ NR¹ R².

When R is or contains halogen or when R¹, R² or R³ contains halogen, itis preferably fluorine, bromine and particularly chlorine.

When two adjacent groups R together with the carbon atoms to which theyare attached form a fused ring, the fused ring is preferably phenyl asin naphthalene which may be substituted as described for R.

When R¹ and R² together with the nitrogen atom to which they areattached form a ring the ring preferably contains 6 atoms as for examplemorpholinyl, piperidinyl, piperazinyl and N--(C₁₋₆ -alkyl)piperazinyl.

It is preferred that R is unsubstituted alkyl or two adjacent groups Rtogether with the carbon atoms to which they are attached form a fusedphenyl ring optionally substituted by alkyl groups.

In one preferred embodiment, n is zero and the AHCAM is a derivative ofsalicyclic acid.

In a further preferred embodiment, two adjacent groups R together withthe carbon atoms to which they are attached form a fused ring,especially a fused phenyl ring as in naphthalene. It is particularlypreferred that the naphthalene ring contains no substituents R.

The groups R¹, R² and/or R³ are selected primarily to improve thecompatibility of the AHCAM with the toner resin with which they areformulated. Thus, the size and length of the groups R¹ to R³ may beselected to improve the physical entanglement or intercolation of theAHCAM with the resin or they may contain reactive entities capable ofreacting chemically with the resin.

Preferably, R¹, R² and/or R³ is or contains a saturated aliphatic chainand it is particularly preferred that the total number of carbon atomsis greater than four and preferably greater than 10. Preferably, thetotal number of aliphatic carbon atoms in R¹, R², and/or R³ is less than30, more preferably less than 24 and especially less than 18.

It is also preferred that R¹ is unsubstituted hydrocarbyl and especiallyunsubstituted alkyl.

In one preferred embodiment R³ is hydrogen.

In a particularly preferred embodiment, the AHCAM is present as a saltor metal complex. The salt may be that of a primary, secondary ortertiary amine or a quatemary ammonium compound (hereinafter QAC).Preferred amines or QAC's are those containing C₁₋₂₄ -alkyl chains,particularly where the alkyl chain contains more than 6 and especiallymore than 10 carbon atoms since these amines or QAC's are less volatileand are more resistant to the high temperature employed in thefabrication of toner resin compositions. Examples of amines and QACcations are dodecylamine, octadecylamine, didecylamine, didodeceylamine,tetradecylamine, dodecylamine, hexadecylamine, C₁₂₋₁₈ -mixed alkylaminesand their N--C₁₋₆ -alkyl or N,N-di-C₁₋₆ -alkyl derivatives or N-benzylderivatives, and particularly their methyl or ethyl derivatives, andN,N-diethyl-N-dodecyl-N-benzylammonium;N,N-dimethyl-N-octadecyl-N-(dimethylbenzyl)ammonium;N,N-dimethyl-N,N-didecylammonium; N,N-dimethyl-N,N-didodecylammonium;N,N,N-trimethyl-N-tetradecylammonium; N-benzyl-N,N-dimethyl-N-(C₁₂₋₁₈ -₁-alkyl)ammonium; N-(dichlorobenzyl)-N,N-dimethyl-N-dodecylammonium;N-hexadecylpyridinium; N-hexadecyl-N,N,N-trimethylammonium;dodecylpyridinium; N-benzyl-N-dodecyl-N,N-bis(hydroxyethyl)ammonium;N-dodecyl-N-benzyl-N,N-dimethylammonium; N-benzyl-N,N-dimethyl-N-(C₁₂₋₁₈-alkyl)ammonium; N-dodecyl-N,N-dimethyl-N-(1-naphthylmethyl)ammonium andN-hexadecyl-N,N-dimethyl-N-benzylammonium cations.

In an especially preferred embodiment the AHCAM is present as a salt orcomplex of a mono-, di- or trivalent metal. Preferred metals are thoseof groups 1a, 2a, 3a, 1b, 2b, 6b, 7b, and 8 of the Periodic Tableaccording to Mendeleef as for example published in the inside rear coverof the Handbook of Chemistry and Physics published by The ChemicalRubber Co, Ohio, USA. Especially preferred metals are Mg, Ca, Ba, Cr,Mn, Fe, Co, Ni, Cu, Zn and Al. Metal salts or complexes derived fromMg(II), Ca(II), Ba(II), Zn(II) and Al(III) have the specific advantagethat they are substantially colorless and such compounds may be used asCCA's for making colored images whereas compounds derived from Cr(III)and Fe(III) tend to be strongly colored and hence such CCA's are mainlyof use for forming black images.

The salt or complex of the AHCAM can include more than one cation. Thus,it may comprise more than one metal or a combination of a metal togetherwith an amine or QAC such that the salt or complex is a neutralmolecule. It is preferred, however, that the salt or complex of theAHCAM is that of a metal.

The toner resin is a thermoplastic resin suitable for use in thepreparation of toner compositions. A preferred toner resin is a styreneor substituted styrene polymer or copolymer such as polystyrene orstyrene-butadiene copolymer.

It is especially preferred that the toner resin is a styrene-acryliccopolymer such as a styrene-butyl methacrylate copolymer. Other suitabletoner resins are polyesters, especially alkoxylated bis-phenol basedpolyester resins such as those described in U.S. Pat. No. 5,143,809,polyvinyl acetate, polyalkenes, poly(vinyl chloride), polyurethanes,polyamides, silicones, epoxy resins and phenolic resins. Furtherexamples of these and other resins are given in the book"Electrophotography" by R. M. Shafert (Focal Press); UK 2,090,008, U.S.Pat. No. 4,206,064 and U.S. Pat. No. 4,407,924.

The toner resin composition may contain more than one AHCAM. The ACHAMis preferably present in the composition from 0.1 to 12%, morepreferably from 0.5 to 10% and especially from 1 to 3% by weight of thetotal composition.

The toner resin composition may also contain a dyestuff or pigment ascolorants. Thus, according to a further aspect of the invention there isprovided a toner resin composition as hereinbefore defined which furthercomprises a colorants. The colorants is preferably a pigment such ascarbon black; magnetite; or a metallised phthalc-cyanine, quinacridone,perylene, benzidine, nigrosine, aniline, quinoline or anthraquinonepigment; or an azo disperse dye, benzodifuranone, metallised lake orpigment toner or water insoluble salt of a basic dye, including mixturesthereof. The colorants may also be a water soluble basic dye, especiallya triphenylmethane dyestuff. The toner composition may contain up to 20%colorants and especially from 3 to 10% relative to the total weight ofthe toner resin composition.

When the colorant comprises magnetites or a mixture of magnetites andcolored pigment the colorants is preferably present from 5 to 70% andmore preferably from 10 to 50% by weight of the toner resin composition.Mixtures of carbon black and magnetite are available commercially andthose containing from about 1 to 15% are preferred, especially thosecontaining from 2 to 6% carbon black based on the weight of carbon blackand magnetite.

The toner resin composition may be prepared by any method known to theart which typically involves mixing the toner resin with the AHCAM andoptionally the colorants by kneading in a ball mill above the meltingpoint of the resin. Generally, this involves mixing the moltencomposition for several hours at temperatures from 120 to 200° C., inorder to uniformly distribute the AHCAM and colorants (if present)throughout the toner resin. The toner resin is then cooled, crushed andmicronised until the mean diameter of the particles is preferably below20μ and, for high resolution electroreprography, more preferably from 1to 10μ. The powdered colour toner or toner-resin so obtained may be useddirectly or may be diluted with an inert solid diluent such as finesilica by mixing for example in a suitable blending machine.

As noted hereinbefore many of AHCAM's including the salts and or metalcomplexes thereof, are new.

Thus, according to a still further aspect of the invention there isprovided a AHCAM obtainable by reacting a AHCA with formaldehydeoptionally in the presence of an amine, including a salt or metalcomplex thereof with the exception of4-hydroxymethyl-3hydroxy-2-naphthoic acid and pamoic acid.

The AHCAM may be prepared by any method known to the art but ispreferably made by dissolving the AHCA in aqueous alkali and adding therequisite amount of formaldehyde optionally in the presence of an amine.The AHCAM can then be conveniently isolated by neutralisation andseparated in conventional manner for example by filtration. Thesolubility of the AHCA in aqueous alkali can be increased wherenecessary by including a water-miscible co-solvent. However, this is notgenerally necessary.

The amount of formaldehyde used is preferably between 1.0 and 1.10 molesbased on the molar concentration of the AHCA for each methylene groupinserted into the AHCA When the reaction is carried out in the presenceof an amine of formula HNR¹ R² as under typical Mannich reactionconditions the amount of the amine is preferably the same as the molarconcentration of formaldehyde.

The reaction is very facile and is preferably carried out at atemperature below 100° C. and especially below 80° C. Preferredtemperatures are above 20° C., more preferably above 30° C. andespecially above 50° C.

Examples of suitable AHCA are salicylic acid, 5-methyl-, 5-tertbutyl,5-nonyl- and 5-dodecyl salicylic acid. Examples of suitable AHCcontaining a fused ring are 2-hydroxy-3-naphthoic including the5-tertbutyl and 5,7-ditert. butyl derivatives, 2-hydroxy-1-naphthoic,1-hydroxy-2-naphthoic and 8-hydroxy-1-naphthoic acids.

Examples of suitable amines of formula HNR¹ R² are N-methyl ethylamine,N,N-diethylamine, N,N-dibutylamine, N,N-dihexylamine,N-methyl-2-ethylhexylamine, N-methyl-2-ethylbutylamineN,N-diethanolamine and N-methyl-ethanolamine.

When R³ is other than hydrogen, the AHCAM of formula 1 is preferablymade by reacting the AHCAM of formula 1 wherein R is H with anappropriate alkyl or aralkyl halide, especially a bromide, in a suitableliquid in the presence of a base. Preferably, the liquid is wateroptionally containing a water-miscible solvent and preferred bases arealkali-metal hydroxides such as sodium and potassium hydroxide.

The metal salts or complexes are typically made by dissolving the AHCAMin aqueous alkali and adding an aqueous solution of the desiredinorganic metal salt. Typically the inorganic metal salt is a chloride,nitrate or sulphate. The metal salt or complex generally separates fromthe aqueous alkaline solution and can be isolated by standard methodssuch as filtration.

It will be readily apparent that the metal salt or complex can beproduced in situ without the need to first isolate the AHCAM.

The preferred metals are Mg(II), Ba(II), Fe(III), Al(III) and especiallyZn(II) which are typically used as their chloride salt. Zn(II) can alsobe added as its sulphate.

As noted hereinbefore, the AHCAM including the salt or metal complexthereof can be used as a CCA.

According to a further aspect of the invention there is provided the useof a AHCAM, including salts and metal complexes thereof as a CCA withthe exception of pamoic acid.

Useful effects have been obtained with the 2:1 metal salt or complex of4-hydroxymethyl-3-hydroxy-2-naphthoic acid with zinc or calcium; the 2:1metal salt or complex of4-(N-methyl-N-hydroxyethyl)aminomethyl-3-hydroxy-2-naphthoic acid withzinc and the 3:1 iron complex of4-(N-methyl-N-hydroxyethyl)aminomethyl-3-hydroxy-2-naphthoic acid.

The invention is further illustrated by the following examples whereinall references are to parts by weight unless indicated to the contrary.

EXAMPLE 1 Preparation of 4-hydroxymethyl-3-hydroxy-2-naphthoic acid

3-hydroxy-2-naphthoic acid (60.8 parts, 0.33M, ex Aldrich) was stirredin 400 mls water. Concentrated sodium hydroxide solution (56 partscontaining 47% sodium hydroxide, 0.66M) was added and the acid dissolvedby heating to about 70° C. This solution was then cooled to 10-12° C.and 37% aqueous formaldehyde (31 parts; 0.38M) was added rapidly.

After stirring for a further 3 hours at 14-16° C. the reaction mass wasdischarged into ice/water (500 parts) and the pH adjusted to about 3.5by addition of strong sulphuric acid when the product separated. Thiswas isolated by filtration, washed with water and dried. Yield=71.6parts (98% theory) mp 285-95° C.

Elemental analysis: C₁₂ H₁₀ O₄ (0.5 H₂ 0) requires 63.4%C, 4.8%H; Found63.4%C, 4.7%H;

Proton NMR: (D₂ 0/DMSO) δ 5.0 (s, 24, --CH₂ 0--); 7.4-8.5(m, 5H,aromatic)

EXAMPLE 2 Preparation of the 2:1 zinc salt of4-hydroxymethyl-3-hydroxy-2-naphthoic acid

4-hydroxymethyl-3-hydroxy-2-naphthoic acid (2.18 parts; 0.01M; exExample 1) was stirred in water (7 parts) containing sodium hydrogencarbonate (0.84 parts; 0.01M). After cooling to 18-24° C., a smallamount of 2N sodium carbonate solution was added to adjust the pH to8.8-9.0 whereupon the acid dissolved.

A solution of zinc sulphate heptahydrate (2 parts; ex Aldrich) in water(4 parts) was slowly added and the reaction stirred for a further 1 hourat 18-24° C. A pale cream suspension was immediately formed and wasfiltered, washed with water and dried.

Yield=1.69 parts (62.7% theory) mp>300° C. This is CCA 1.

Elemental analysis: Found 53.4%C, 3.4%H, 12.30%Zn; (C₁₂ H₉ 0₄)₂ Zn(2.2H₂ 0) requires 53.4%C; 4.2%H; 12.1% Zn.

EXAMPLE 3 Preparation of4-(N-methyl-N-hydroxyethyl)aminomethyl-3-hydroxy-2-naphthoic acid

3-hydroxy-2-naphthoic acid (18.8 parts, 0.1M, ex Aldrich), water (50 ml)and N-methylethanolamine (12.8 parts, 0.17M, ex Fluka) were stirredtogether at 20-25° C. to give a clear solution. After heating to 80° C.,formaldehyde (10 mls at 37/40% strength by volume, 0.1M ex FSA labs) wasadded over 10 minutes with stirring at 80-85° C.

After stirring for a further 3 hours at 80-85° C., the reactants werecooled and the pH of the solution adjusted to pH 3-4 by addition of 2Msulphuric acid solution whereupon the product separated as an off-whitesolid. This was filtered, washed with water and dried.

Yield=23.6 parts (86% theory) mp 127-129° C.

Elemental analysis Found 61.4%C, 6.5%H, 4.7%N; C₁₅ H₁₇ NO₄ requires65.4%C, 6.2%H, 5.1%N

EXAMPLE 4 Preparation of the 2:1 salt or complex of4-(N-methyl-N-hydroxyethyl) aminomethyl-3-hydroxy-2-naphthoic acid withzinc

The naphthoic acid from Example 3 (22.02 parts, 0.08M) was stirred at50-60° C. in water (175 mls) containing sodium hydroxide (3.2 parts,0.08M) to dissolve the acid. A solution of zinc chloride (5.45 parts,0.04M) in water (8mls) was then added at 50-60° C. whereupon the zincsalt or complex immediately separated. After cooling to 20-25° C., theproduct was filtered, washed with water and dried.

Yield=20.58 parts (84% theory) mp>250° C. This is CCA 2.

Elemental analysis was consistent with the required product as thetrihydrate.

EXAMPLES 5 and 6 Preparation and evaluation as CCA

A styrene/acrylic resin (300 parts, Almacryl B-1500 ex Image PolymersEurope) and CCA (7.5 parts) were melt kneaded at 160-180° C. for 60minutes. The resulting toner was then cooled, crushed and finally groundby ball-milling until an average particle size between 5 and 25μ wasobtained.

The milled toner (0.4 parts) was then mixed with an uncoated iron powdercarrier (19.6 parts, RAV-270 ex Powder Tech Corporation, Valparaiso,Ind., USA) in an aluminium tin for 30 minutes on a roller mill.

The resulting CCA was then evaluated using a Toshiba TB 200 blow-offapparatus and the tribo-harge measured after various time intervals. Theresults are given in Table 1 below.

                  TABLE 1    ______________________________________                Tribo-charge (μCg.sup.-1) after time(mins)    Example           CCA        5       10      20    30    ______________________________________    5      1 (Ex 2)   -18     -21     -26   -29    6      2 (Ex 4)   ND      -19     -21   -24    ______________________________________

Footnote to Table 1ND=not determined

EXAMPLE 7 Preparation of the 3:1 iron salt of4-(N-methyl-N-2-hydroxyethyl)aminomethyl-3-hydroxy-2-naphthoic acid

Ferric chloride hexahydrate (13.52 parts ex Fisons; 0.05M) was dissolvedin water with stirring at 50 to 55° C. The naphthoic acid (39.15 parts,0.142M) as prepared in Example 3 was added and immediately dissolvedgiving a very dark solution. 2N Sodium hydroxide solution (255 ml) wasadded in portions with stirring at 55 to 60° C. to give a pH of about4.25 when a dark brown precipitate gradually formed. The pH was thenadjusted to about pH 6 by stirring at 20 to 25° C. with addition of 2Nsodium hydroxide solution. The resulting brown solid was filtered,dissolved in hot methanol (600 mls) and the solution screened. Afterevaporation of the methanol the product was obtained as a dark-brownsolid (39.15 parts).

Elemental analysis

Theory: 61.5% C, 5.5% H, 4.8% N, 6.4% Fe;

Found: 56.7% C, 5.0% H, 4.4% N, 6.0% Fe.

The sample contained 1.4% (w/w) water as determined by drying toconstant weight at 60° C. and 0.2% (w/w) bound water as determined byKarl Fischer titration. This corresponds to a 92.2% (w/w) strength forthe iron salt.

The iron salt was formulated as a toner by the method described inExamples 5 and 6 and the tribo electric charge measured using a ToshibaTB 200 blow-off apparatus. The tribocharge (μCg⁻¹) after 5,10,20 and 30minutes was found to be -17.51, -21.80, -25.91 and -27.04 respectively.

EXAMPLE 8 Preparation of the 2:1 calcium salt of4-(N-methyl-N-hydroxyethyl)aminomethyl-3-hydroxy-2-naphthoic acid

The naphthoic acid prepared as described in Example 3 (13.75 parts,0.05M) was dissolved in water (100 ml) containing sodium hydroxide (2parts, 0.05M) by stirring at 20 to 25° C. The solution was heated to 55to 60° C. and a solution of calcium chloride dihydrate (3.78 parts,0.025M) dissolved in water (5 ml) was added dropwise over 10 minutes.After stirring for a further 30 minutes at 55-60° C., the reaction mixwas allowed to cool and the product filtered, washed with water anddried. The calcium salt was obtained as a bright yellow solid (10.91parts) mp>300° C. Elemental analysis

Theory: 61.2% C, 5.4% H, 4.8% N, 6.8% Ca;

Found: 56.7% C, 6.2% H, 4.1% N, 7.2% Ca

The solid was found to contain 5.5% (w/w) water by Karl Fischertitration.

EXAMPLE 9 Preparation of the 2:1 calcium salt of4-hydroxymethyl-3-hydroxy-2-naphthoic acid

The naphthoic acid prepared as described in Example 1 (21.8 parts, 0.1M)was dissolved in water (150 ml) containing sodium hydroxide (4 parts,0.1M) with stirring at 15 to 20° C. Calcium chloride dihydrate (7.35parts, 0.05M) dissolved in water (10 ml) was added dropwise over 10minutes with stirring at 15 to 20° C. After stirring for a further 60minutes, the resultant solid was filtered, washed with water and driedat 20 to 25° C. over anhydrous calcium chloride under reduced pressure.Yield=3.0 parts, mp>300° C.

Elemental analysis

Theory: 60.7% C, 3.8% H, 8.5% Ca;

Found: 55.4% C, 3.9% H, 9.2% Ca

The solid was found to contain 8.4% (w/w) bound water by Karl Fischertitration.

We claim:
 1. A toner comprising solid particles having a mean diameterof less than 20 microns, which comprise a thermoplastic toner resin andan aromatic carbocyclic hydroxy carboxylic acid having at least onemethylene group substituted by hydroxy or optionally substituted aminoincluding salts and metal complexes thereof.
 2. A toner as claimed inclaim 1 wherein the carboxylic acid group is attached to a carbon atomadjacent to that carrying the hydroxy group in the aromatic carbocyclichydroxy carboxylic acid.
 3. A toner as claimed in claim 1, where thearomatic carbocyclic hydroxy carboxylic acid is a compound of Formula 1:##STR4## or salt or metal complex thereof; where X is hydroxy, or --NR¹R² R is halogen, hydroxy, nitro, carboxy, nitrile, optionallysubstituted C₁₋₁₈ hydrocarbyl, or two adjacent groups R together withthe carbon atoms to which they are attached form an optionallysubstituted 5- or 6-membered fused ring; n is 0 to 3; R¹ and R² is each,independently, hydrogen, optionally substituted C₁₋₁₈ hydrocarbyl or R¹and R² together with the nitrogen atom to which they are attached form aring; and R³ is hydrogen, aralkyl or optionally substituted C₁₋₁₈ alkyl.4. A toner as claimed in claim 3 wherein R¹ and R² are not bothhydrogen.
 5. A toner as claimed in claim 3 wherein two adjacent groups Rform an optionally substituted fused phenyl ring.
 6. A toner as claimedin claim 3 wherein R³ is hydrogen.
 7. A toner as claimed in claim 1 orclaim 3 wherein the aromatic carbocyclic hydroxy carboxylic acidcompound of claim 1 or the compound of formula (1) of claim 3 is a saltor complex of a metal selected from group 1a, 2a, 3a, 1b, 2b, 6b, 7b, or8 of the Periodic Table.
 8. A toner as claimed in claim 7 wherein themetal is zinc, calcium or iron.
 9. A toner as claimed in claim 1 whichfurther comprises a colorant.
 10. A compound selected from the groupconsisting of:the 2:1 salt of4-(N-methyl-N-hydroxyethyl)aminomethyl-3-hydroxy-2-naphthoic acid andzinc; the 2:1 salt of4-(N-methyl-N-hydroxyethyl)aminomethyl-3-hydroxy-2-naphthoic acid andcalcium; and the 3:1 salt of4-(N-methyl-N-hydroxyethyl)aminomethyl-3-hydroxy-2-naphthoic acid andiron.
 11. A method for improving the tribo-electric chargecharacteristics of a toner for electroreprographic image processes,comprising:preparing a toner resin composition by mixingi) athermoplastic resin, and ii) from 0.1% to 12% by weight, based on thetotal weight of the toner resin composition, of an aromatic carbocyclichydroxy carboxylic acid having at least one methylene group substitutedby hydroxy or optionally substituted amino including salts and metalcomplexes thereof; kneading said mixture; cooling said kneaded mixture;crushing the cooled mixture; and micronizing the crushed mixture toobtain a toner comprising solid particles having a mean diameter of lessthan 20 microns.
 12. A process for making an electroreprographic imagecomprising:developing a latent electrostatic image with a tonercomprising a thermoplastic toner resin and a negative charge controlagent wherein the negative charge control agent is an aromaticcarbocyclic hydroxy carboxylic acid having at least one methylene groupsubstituted by hydroxy or optionally substituted amino including saltsand metal complexes thereof.